Weather Radar Fundamentals

Navigation Menu

Common Clear Air Phenomena » Non-Meteorological Returns » Sea Clutter

A radar reflectivity image shows a large grainy-looking area of low-intensity echo just to the west of a coastline.
A radial velocity image shows a region of low inbound velocities just to the west of a shoreline

Sea clutter results from radar beams intersecting with waves and sea spray on lakes, seas, and oceans. This phenomenon occurs most often during times of rough seas and can be compounded when superrefraction occurs.

Usually, sea clutter has the following characteristics on radar:

  • Low reflectivity values
  • Usually present in only the lowest scans
  • A fine, slightly grainy texture
  • Echoes generally persist in their location and intensity
  • Radial velocity shows prevailing wind direction, as waves and spray move with the wind